Research in Epstein's laboratory is concerned with four aspects of the neuropsychology of ingestive behavior: the chemical controls of 1) thirst, and 2) sodium appetite, 3) the chemical controls of food satiety, and 4) the ontogeny of ingestive behavior. We are emphasizing the role of angiotension in the mobilization of thirst of extracellular depletions, and in the arousal of sodium appetite. The receptor site within the brain for the dipsogenic action of angiotension is being sought with particular attention to the subfornical organ. The role of the peptide in sodium appetite is being studied in the context of an hypothesis that predicts that the appetite is aroused by a synergy of angiotensin and its companion hormone aldosterone. Recently discovered antidipsogens (prostaglandin E, Substance P) are being investigated for their selective competitive interaction with the dipsogenic action of antiotensin. Our approach to the study of the chemical controls of food intake employs physiological doses of catecholamines in an analysis of the possible adrenergic mechanism for the arousal and suppression of the brain mechanisms for meal-taking. The ontogeny of feeding and drinking is being studied in suckling and weanling rats with both appetitive and consumatory testing. The chronology of development of the separate physiological controls of each mode of ingestive behavior will be described and their assembly into adult feeding and drinking analyzed.